Key to third-instar chrysomyinae (Diptera: Calliphoridae) from carrion in the continental United States

Molecular identification of Chrysomya albiceps (Diptera: Calliphoridae) in a case of primary cutaneous myiasis in sheep at southern Brazil

Sheep farming has been growing in Brazil, driven by an expanding consumer market due to greater acceptance of its meat and derivatives. There are several factors that limit sheep production, and one of them is infestation by ectoparasites, which cause stress in animals, weight loss, poor development, low productivity, low quality wool and reduced fertility. Chrysomya albiceps is a species of blowfly belonging to the Calliphoridae family that occurs in neotropical regions, where it causes secondary myiasis. We identified here a rare case of cutaneous myiasis with the presence of tissue lesions caused by C. albiceps in sheep in southern Brazil. We highlight the need to carry out more in-depth studies regarding the biology of these insects, with the aim of proving this atypical behavior for Brazil.

Simplified COI barcoding of blow, flesh, and scuttle flies encountered in medicolegal investigations

Accurate insect identification is critical to the estimation of time of colonization (TOC) and post-mortem interval (PMI) in medicolegal death investigations. DNA testing is advantageous because it enables the identification of immature specimens that may not be identified based on morphology alone. We describe here a simplified DNA barcoding method for identifying relevant species that may be implemented by forensic genetics laboratories. A cytochrome oxidase (COI) fragment is analyzed after PCR amplification with a single primer set. The method is effective for many species commonly encountered in death investigations in the USA: members of blowfly genera Calliphora, Chrysomya, Cochliomyia, Lucilia, and Phormia; members of the flesh fly genera Blaesoxipha, Oxysarcodexia, Ravinia, and Sarcophaga; and the scuttle fly Megaselia scalaris. We tested the method on specimens with verified identifications and used it to build a collection of reference sequences from specimens collected in Harris County, Texas. We show here the correct identification of larvae, pupae, and pupal exuviae from the medicolegal casework.

Key for the identification of third instar larvae of African blowflies (Diptera: Calliphoridae) of forensic importance in death investigations

Blowfly larvae are the insects primarily responsible for the active stage of decomposition of exposed vertebrate remains and are the most frequently collected entomological evidence during forensic investigations of death. The necrophagous calliphorids in continental Africa that consistently develop on large vertebrate carrion include 11 species belonging to four genera: Calliphora, Chrysomya, Hemipyrellia and Lucilia. Most of these species are widespread in Africa and frequently reported on large animal carcasses and carrion and human corpses. A few keys have been compiled for identification of their third instar larvae, but none of them covers the complete set of taxa. Therefore, we provide a new comprehensive key with original illustrations of all taxonomically significant characters. The key is based on characters that should be easily observable even in poorly equipped local laboratories and is a reliable taxonomic tool for material collected in either urban or rural areas where synanthropic species predominate. However, it should be used with some caution in areas with relatively pristine natural habitats, where additional carrion-breeding species may occur. The publication of the key will significantly facilitate both medical and forensic entomological research and practice in Africa.

Not by the Book: Observations of Delayed Oviposition and Re-Colonization of Human Remains by Blow Flies

Postmortem interval estimations can be complicated by the inter-individual variation present in human decomposition. Forensic entomologists may especially face challenges interpreting arthropod evidence in scenarios that are not "by the book", or that vary in unexpected ways. Therefore, it is important to report instances where blow fly colonization does not align with expected soft tissue decomposition as blow fly larvae are often used to produce a time of colonization (TOC) estimation to infer a minimum PMI. We followed the decomposition and blow fly activity of three human donors at the Anthropology Research Facility (University of Tennessee). Delayed oviposition occurred on one donor 115 d post-placement, whereas two donors experienced blow fly re-colonization after cessation of the consumption phase, one 22 d and one more than 200 d after blow fly larvae were last observed. A null hypothesis model tested whether the entomological TOC and anthropological total body score (TBS) estimations encompassed the time of placement (TOP) for each donor. While the null hypothesis was rejected for all TOC estimations, it could not be rejected for the TBS estimations. We discuss how the non-linear nature of human decomposition can pose challenges to interpreting blow fly evidence and suggest that forensic entomology practitioners should recognize these limitations in both research endeavors and applied casework.

Technical note: A technique to mount Sarcophagidae and Calliphoridae (Diptera) larvae for forensic identification using geometric morphometrics

Geometric morphometric analyses use landmark coordinates from images of specific areas on specimens. Therefore, to minimize differences arising from human preparation, preparation of the specimen is crucial. The application of geometric morphometrics has been used in entomology for identifying adult dipteran species, however, applying this technique to larval specimens requires the production of standard protocols which would allow specimens to be compared equally. This proposed protocol consists of a two-step process:

1. using 15% potassium hydroxide (KOH) to clear the specimen, followed by rinsing the specimen with 80% ethanol;

2. removal and spreading of the mouthhooks on a slide for imaging and analysis.

The goal of this work is to standardize specimen preparation, which would reduce human error and facilitate use of geometric morphometrics to identify dipteran larvae.

Description of Larval Instars To Fill a Gap in Forensic Entomology: The Larvae of Paralucilia pseudolyrcea (Diptera: Calliphoridae)

A fundamental assumption of forensic entomology for estimating the postmortem interval is that insect species are accurately identified, which depends on diagnostic morphological characters. Larvae of the blow fly Paralucilia pseudolyrcea (Mello, 1969) (Diptera: Calliphoridae) were sampled from four corpses in the state of Paraná, Brazil, but despite the forensic importance of this species, morphological data for the identification of its larval instars are lacking, limiting its usefulness in such cases. Thus, the main goal of this study was to describe the larval instars of P. pseudolyrcea. The material was obtained from a colony established by larvae collected from a corpse of a murder case. Overall, the distribution of spines is a key character for identifying this species in the first, second and third instars. Other characteristics, such as the presence of an accessory oral sclerite, the small cirri, the number of lobes of the anterior spiracle and the morphology of posterior spiracles, separates P. pseudolyrcea from other necrophagous blow flies. The detailed morphological description provided here facilitates the identification of larval instars of P. pseudolyrcea and their differentiation from those of other calliphorid species.

DNA-barcoding of forensically important blow flies (Diptera: Calliphoridae) in the Caribbean Region

Correct identification of forensically important insects, such as flies in the family Calliphoridae, is a crucial step for them to be used as evidence in legal investigations. Traditional identification based on morphology has been effective, but has some limitations when it comes to identifying immature stages of certain species. DNA-barcoding, using COI, has demonstrated potential for rapid and accurate identification of Calliphoridae, however, this gene does not reliably distinguish among some recently diverged species, raising questions about its use for delimitation of species of forensic importance. To facilitate DNA based identification of Calliphoridae in the Caribbean we developed a vouchered reference collection from across the region, and a DNA sequence database, and further added the nuclear ITS2 as a second marker to increase accuracy of identification through barcoding. We morphologically identified freshly collected specimens, did phylogenetic analyses and employed several species delimitation methods for a total of 468 individuals representing 19 described species. Our results show that combination of COI + ITS2 genes yields more accurate identification and diagnoses, and better agreement with morphological data, than the mitochondrial barcodes alone. All of our results from independent and concatenated trees and most of the species delimitation methods yield considerably higher diversity estimates than the distance based approach and morphology. Molecular data support at least 24 distinct clades within Calliphoridae in this study, recovering substantial geographic variation for Lucilia eximia, Lucilia retroversa, Lucilia rica and Chloroprocta idioidea, probably indicating several cryptic species. In sum, our study demonstrates the importance of employing a second nuclear marker for barcoding analyses and species delimitation of calliphorids, and the power of molecular data in combination with a complete reference database to enable identification of taxonomically and geographically diverse insects of forensic importance.

Post-Colonization Interval Estimates Using Multi-Species Calliphoridae Larval Masses and Spatially Distinct Temperature Data Sets: A Case Study

Common forensic entomology practice has been to collect the largest Diptera larvae from a scene and use published developmental data, with temperature data from the nearest weather station, to estimate larval development time and post-colonization intervals (PCIs). To evaluate the accuracy of PCI estimates among Calliphoridae species and spatially distinct temperature sources, larval communities and ambient air temperature were collected at replicate swine carcasses (N = 6) throughout decomposition. Expected accumulated degree hours (ADH) associated with Cochliomyia macellaria and Phormia regina third instars (presence and length) were calculated using published developmental data sets. Actual ADH ranges were calculated using temperatures recorded from multiple sources at varying distances (0.90 m–7.61 km) from the study carcasses: individual temperature loggers at each carcass, a local weather station, and a regional weather station. Third instars greatly varied in length and abundance. The expected ADH range for each species successfully encompassed the average actual ADH for each temperature source, but overall under-represented the range. For both calliphorid species, weather station data were associated with more accurate PCI estimates than temperature loggers associated with each carcass. These results provide an important step towards improving entomological evidence collection and analysis techniques, and developing forensic error rates.

Comparing Species Composition of Passive Trapping of Adult Flies with Larval Collections from the Body during Scene-Based Medicolegal Death Investigations

Collection of insects at the scene is one of the most important aspects of forensic entomology and proper collection is one of the biggest challenges for any investigator. Adult flies are highly mobile and ubiquitous at scenes, yet their link to the body and the time of colonization (TOC) and post-mortem interval (PMI) estimates is not well established. Collection of adults is widely recommended for casework but has yet to be rigorously evaluated during medicolegal death investigations for its value to the investigation. In this study, sticky card traps and immature collections were compared for 22 cases investigated by the Harris County Institute of Forensic Sciences, Houston, TX, USA. Cases included all manner of death classifications and a range of decomposition stages from indoor and outdoor scenes. Overall, the two methods successfully collected at least one species in common only 65% of the time, with at least one species unique to one of the methods 95% of the time. These results suggest that rearing of immature specimens collected from the body should be emphasized during training to ensure specimens directly associated with the colonization of the body can be identified using adult stages if necessary.

Chemotaxonomic Profile and Intraspecific Variation in the Blow Fly of Forensic Interest Chrysomya megacephala (Diptera: Calliphoridae)

Necrophagous insects such as blow flies (Diptera: Calliphoridae) are considered crucial in forensic entomology. Identification at species level and determination of larval stage are the basis for estimation of postmortem interval (PMI). Insect evidence can also be used in the determination of crime scenes, since body displacement is common. The aim of this study was to determine the chemotaxonomic profile and intraspecific variability of the forensically important blow fly Chrysomya megacephala (F. 1794). Adults were collected in the municipalities of Dourados-MS (Brazil) and Rio Claro-SP (Brazil), and then transferred to the laboratory for oviposition and development of the immature stages. Chemical analysis of cuticular compounds was performed by gas chromatography. Cuticular chemical profiles varied significantly between the two populations, as well as between developmental stages, supporting the use of these compounds as a complementary tool to help identify the species and its stages, along with geographical variability. This could greatly accelerate forensic investigations, eliminating the need to allow the fly larvae to develop until adult stage in order to confirm the species identity and sample origin.

Molecular identification of necrophagous muscidae and sarcophagidae fly species collected in Korea by mitochondrial cytochrome C oxidase subunit I nucleotide sequences

Identification of insect species is an important task in forensic entomology. For more convenient species identification, the nucleotide sequences of cytochrome c oxidase subunit I (COI) gene have been widely utilized. We analyzed full-length COI nucleotide sequences of 10 Muscidae and 6 Sarcophagidae fly species collected in Korea. After DNA extraction from collected flies, PCR amplification and automatic sequencing of the whole COI sequence were performed. Obtained sequences were analyzed for a phylogenetic tree and a distance matrix. Our data showed very low intraspecific sequence distances and species-level monophylies. However, sequence comparison with previously reported sequences revealed a few inconsistencies or paraphylies requiring further investigation. To the best of our knowledge, this study is the first report of COI nucleotide sequences from Hydrotaea occulta, Muscina angustifrons, Muscina pascuorum, Ophyra leucostoma, Sarcophaga haemorrhoidalis, Sarcophaga harpax, and Phaonia aureola.

Larval Distribution and Behavior of Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) Relative to Other Species on Florida Black Bear (Carnivora: Ursidae) Decomposing Carcasses

Larval interactions of dipteran species, blow flies in particular, were observed and documented daily over time and location on five black bear carcasses in Gainesville, FL, USA, from June 2002 - September 2004. Cochliomyia macellaria (Fabricius) or Chrysomya megacephala (Fabricius) larvae were collected first, after which Chrysomya rufifacies (Macquart) oviposited on the carcasses in multiple locations (i.e., neck, anus, and exposed flesh) not inhabited already by the other blow fly larvae. Within the first week of decomposition, C. rufifacies larvae grew to ≥12 mm, filling the carcasses with thousands of larvae and replacing the other calliphorid larvae either through successful food source competition or by predation. As a result, C. macellaria and C. megacephala were not collected past their third instar feeding stage. The blow fly species, C. megacephala, C. macellaria, Lucilia caeruleiviridis (Macquart), Phormia regina (Meigen), Lucilia sericata (Meigen), and C. rufifacies, completed two developmental cycles in the 88.5-kg carcass. This phenomenon might serve to complicate or prevent the calculation of an accurate postmortem interval.

A fly in the ointment: evaluation of traditional use of plants to repel and kill blowfly larvae in fermented fish

Introduction

In rural areas in Laos, fly larvae infestations are common in fermenting fish. Blowflies (Chrysomya megacephala, Diptera: Calliphoridae) are attracted to oviposit (and/or larviposit) onto fermenting fish which results in infestations with fly larvae. Knowledge of traditional use of plants to repel larvae during the production of fermented fish is common and widespread in Lao PDR.

Research Questions

How effective are the most salient species in repelling, and killing fly larvae in fermenting fish?

Material and Methods

The three plant species most frequently reported to repel fly larvae during an ethnobotanical survey throughout Lao PDR were tested for repellence and larvicidal activity of fly larvae infesting fermented fish. The lethality and repellence of Tadehagi triquetrum (L.) H. Ohashi (Fabaceae), Uraria crinita (L.) Desv. ex DC. (Fabaceae) and Bambusa multiplex (Lour.) Raeusch. ex Schult. & Schult. f. (Poaceae) were tested in an experimental design using fermenting fish in Vientiane, Lao PDR.

Results

The repellent effect of fresh material of T. triquetrum and U. crinita, and the larvicidal effect of fresh B. multiplex, is significantly more effective than that of dried material of the same species, and the total effect (repellence and larvicidal effect combined) for each of the three species was significantly more effective for fresh than for dry material. Fresh material of T. triquetrum, U. crinita, or B. multiplex added on top of the fermenting fish repelled 50%, 54%, 37%, and killed 22%, 28%, and 40% of fly larvae. The total effect was not significantly different per species at 72%, 82%, and 77%, respectively.

Discussion and Conclusions

The three most salient species are effective in repelling and killing fly larvae in the production of fermented fish, and may be essential to augment food safety during traditional fermentation in open jars.

Diptera of forensic importance in the Iberian Peninsula: larval identification key

A revision of the species and families of sarcosaprophagous flies (Diptera: Calliphoridae, Sarcophagidae, Muscidae, Fanniidae, Drosophilidae, Phoridae, Piophilidae and Stratiomyidae) suitable for forensic purposes in the Iberian Peninsula is presented. Morphological characteristics that allow the accurate identification of third instars of the species present in the Iberian Peninsula are described and presented in the form of a diagnostic key. For larval Calliphoridae, characteristics such as the spines of the body segments were useful for the genus Calliphora whereas features of the anal segment and the cephalopharyngeal skeleton were useful for larvae of Lucilia. Identification of three Chrysominae species present in the Iberian Peninsula is included. For larval Sarcophagidae, characters such as the arrangement and shape of spiracular openings, structures of the anal segment and the cephalopharyngeal skeleton were used for the first time. A new record of Sarcophaga cultellata Pandellé, from a human corpse, is also included as well as recent incursions into the European cadaveric entomofauna such as Synthesiomyia nudiseta (van der Wulp) and Hermetia illucens (Linnaeus). This work provides useful new information that could be applied to forensic investigations in the Iberian Peninsula and in southern Europe.

Differentiation between Lucilia cuprina and Hemipyrellia ligurriens (Diptera: Calliphoridae) larvae for use in forensic entomology applications

Lucilia cuprina and Hemipyrellia ligurriens are forensically important blow flies in many countries. The immature stage, in particular the third instar, of both species are generally similar in morphological appearance. In this study, the use of three main characteristics, the posterior spiracle, the dorsal spines between the first and second thoracic segments, and the cephalopharyngeal skeleton, allows for identification of both fly species, with the number of papillae on anterior spiracle being a supportive characteristic in some cases. Comparison of these characteristics is illustrated in detail.

Morfologia e duração do desenvolvimento pós-embrionário de Chrysomya megacephala (Diptera: Calliphoridae) em condições de laboratório

A morfologia e o tempo de desenvolvimento pós-embrionário de Chrysomya megacephala (Fabricius) criada em condições de laboratório e em dieta de carne bovina, foi descrita e comparada ao de outras espécies. Os parâmetros analisados foram à duração dos instares larvais e a morfologia. Para isso as larvas foram fixadas e preservadas em intervalos de tempo de 2 horas, desde a eclosão das larvas até a 50ª hora, a fim de se determinar o tempo de desenvolvimento de cada estágio. O tempo total de desenvolvimento larval para C. megacephala foi de 98 horas, com média de comprimento 15,51 mm. Essa espécie tem comportamento necrobiontófago e de importância sanitária e médico-legal, usada na estimativa do intervalo post-mortem em investigação criminal.

Cool-weather activity of the forensically important hairy maggot blow fly Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) on carrion in Upstate South Carolina, United States

The hairy maggot blow fly Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) has expanded its range in the United States since its introduction into Texas (ca. 1980) and has been collected in 15 states. We investigated the bionomics of immature and adult C. rufifacies collected from carcasses of a raccoon Procyon lotor (Linnaeus) and white-tailed deer Odocoileus virginianus Zimmerman in Upstate South Carolina during November 2007, and used these insects to estimate the minimum period of insect activity. Puparia of C. rufifacies were collected from deer carrion; 28% were parasitized by Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae). The mean daily ambient temperature during this study was 11.4+/-1.02 degrees C, representing the lowest recorded mean temperature for adult activity of C. rufifacies; adults of C. rufifacies were observed flying among the carcasses at 9.0 degrees C. Although C. rufifacies is considered a warm-weather blow fly, researchers should be aware of its activity at suboptimal conditions, behavior that might aid its expansion into more northern areas.

Succession pattern of carrion-feeding insects in Paramo, Colombia

The minimum postmortem interval can be estimated based on knowledge of the pattern of insect succession on a corpse. To use this approach requires that we take into account the rates of insect development associated with particular climatological conditions of the region. This study is the first to look at insect succession on decomposing carcasses in the high altitude plains (Paramo) in Colombia, at 3035 m above sea level. Five stages of decomposition were designated with indicator species identified for each stage: Callíphora nigribasis at the fresh stage; Compsomyiops verena at the bloated stage; Compsomyiops boliviana during active decay; Stearibia nigriceps and Hydrotaea sp. during advanced decay and Leptocera sp. for dry remains. A succession table is presented for carrion-associated species of the region, which can be used for estimating time since death in similar areas. Compsomyiops boliviana is reported for the first time in Colombia.

Morphological comparison between Chrysomya rufifacies (Macquart) and Chrysomya villeneuvi Patton (Diptera: Calliphoridae) puparia, forensically important blow flies

In Thailand, the hairy maggots of the blow flies, Chrysomya rufifacies (Macquart) and Chrysomya villeneuvi Patton, are of forensic importance. Both flies are closely related species, not only in the morphological appearance of their larvae and puparia, but also on the aggressive feeding habit of the former. In our continuing studies of forensically important flies, identification of immature ones needs particular attention. In this study, we reported the morphological comparison between the puparia of these two blow fly species using scanning electron microscopy (SEM). Observation revealed that the cuticular sculpture of tubercles along the dorsal and lateral segments had markedly different features: with C. rufifacies having many sharp spines assembling only at the tip, while of C. villeneuvi bore stout spines throughout the tubercle. A larger number of globules at the bubble membrane on the dorsolateral border of the fifth segment was found in C. villeneuvi (average 225) than in C. rufifacies (average 35), and more papillae was observed on the anterior spiracle in C. villeneuvi (13-15) than in C. rufifacies (9-12). However, the morphology of distinct net-like patches of the integument and structure of the posterior spiracle of both species were almost identical. Morphological comparison in this study permitted identification of the puparia of both fly species, particularly in areas where they co-exist.

First report of human myiasis caused by Chrysomya megacephala and Chrysomya rufifacies (Diptera: Calliphoridae) in Thailand, and its implication in forensic entomology

We report a forensic entomology case associated with human myiasis in Chiang Mai Province, northern Thailand. The remains of a 53-yr-old-male were concurrently infested with third instars of the two blow fly species, Chrysomya megacephala (F.) and Chrysomya rufifacies (Macquart), near a severe tumor lesion presented on the lower right leg. The presence of third instars, approximately 5 d old, on the day following postmortem indicated that myiasis occurred before death. This is the first report of both fly species acting as a myiasis-producing agent in Thailand. Unsynchronized data between the age of fly larvae due to myiasis premortem and verified age/ condition of the corpse suggest a potential complication and error in the estimation of postmortem interval if other predisposition fly infestations are not considered.

Molecular identification of forensically important blow fly species (Diptera: Calliphoridae) in Taiwan

Forensic entomology is a discipline that mainly uses insects collected in and around corpses to estimate the post-mortem interval in medicocriminal investigations. Among all scavenger and necrophagous insect groups that are related to corpses, blow flies (Diptera: Calliphoridae) are probably most important, not only because they occur in abundant numbers but also because they are one of the earliest groups to find corpses. However, most entomological evidence is strongly dependent on accurate species identification. Because identification allows the proper developmental data and distribution ranges to be applied in criminal investigations, species in Taiwan were surveyed from early 2000 and were identified using molecular data. Currently, eight species have been identified: Chrysomya megacephala (Fabricius), Chrysomya pinguis (Walker), Chrysomya rufifacies (Macquart), Hemipyrellia ligurriens (Wiedemann), Lucilia bazini Séguy, Lucilia cuprina (Wiedemann), Lucilia hainanensis Fan, and Lucilia prophyrina (Walker). We focused on classifying these blow fly species to establish a knowledge basis for further forensic entomological research in Taiwan. Because molecular data are helpful in identifying insect specimens, especially when no specimen of suitable condition for morphological identification is obtained, we extracted mitochondrial cytochrome oxidase subunit I (COI) DNA of the preceding blow fly species to study its application value for their differentiation. The cloning and sequencing of the COI gene (approximately 1,588 base pairs) of these eight species were completed, and the data were analyzed. Preliminary results revealed the high support of congeneric groupings of species by using COI data; these sequences were also shown to be highly conserved within the same species. To actually use the database of COI sequences under various specimen conditions, specific primers were also applied for different insect stages, different segments of adults, and specimens preserved for various times. A molecular primer key was ultimately constructed for the purpose of rapid and accurate species identification at the molecular level regardless of which stage or which part of a blow fly specimen is collected.

Surface ultrastructure of Chrysomya rufifacies (Macquart) larvae (Diptera: Calliphoridae)

The surface ultrastructure of all larval instars of Chrysomya rufifacies (Macquart) is described by means of scanning electron microscopy (SEM). Morphological changes were greatest from the first to the second instar, but less from the second to the third instar. Most of these changes involved the structure of the anterior spiracle, posterior spiracle, integument of the body, and mouthhooks. Modification of the mouthhooks, especially in the third instar, are helpful in explaining the ferocious feeding ability of the older maggots. The common name of "hairy-maggot" for C. rufifacies is only appropriate for the second and third instars because of their elongated tubercles along the body, whereas this name is not descriptive of the first instar that lack tubercles.

Larval fly activity on sunlit versus shaded raccoon carrion in southwestern West Virginia with special reference to the black blowfly (Diptera: Calliphoridae)

Larvae of Phormia regina (Meigen), Phaenicia sp., and Sarcophaga sp. were identified from raccoon carcasses placed in sunlit and shaded areas at a southwestern West Virginia site in May of 2000. Samples of larvae were taken from each carcass at 3-h intervals over a 153-h experimental period. Phormia regina was clearly the dominant species with large numbers of third instars observed at every 3-h collection period from 81 to 153 h on both carcasses. Mean lengths of third-instar P. regina larvae collected from the sunlit carcass were significantly greater than mean lengths of larvae collected from the shaded carcass. Third-instar Phaenicia sp. also appeared at 81 h on both carcasses, but relatively few (< or = 4) individuals were present in each 3-h collection sample from 81 through 126 h. Larvae of this species were not present in samples from either carcass in those 3-h intervals from 129 to 147 h. Sarcophaga sp. larvae were also collected, but only in samples taken from the sunlit carcass at 81 and 93 h. Ambient temperatures were recorded throughout the experimental period, whereas maggot mass temperatures were not recorded until the appearance of large numbers of second instars at 48 h. From 48 to 69 h, maggot mass temperatures were equivalent to ambient temperatures; but after 69 h, maggot mass temperatures were considerably elevated over ambient temperatures.

DNA-based identification of forensically important Chrysomyinae (Diptera: Calliphoridae)

Identifying an insect specimen is an important first step in a forensic-entomological analysis. However, diagnostic morphological criteria are lacking for many species and life stages. We demonstrate a method for using mitochondrial DNA sequence data and phylogenetic analysis to identify any specimen of the blow fly subfamily Chrysomyinae likely to be collected from a human corpse within Canada or the USA. The reliability of the method was illustrated by analyzing specimens designed to mimic the information likely to be obtained from highly degraded specimens as well as specimens collected from widely separated geographic locations. Our sequence database may be suitable for another country provided the investigator knows the local fly fauna well enough to narrow the choice of chrysomyine species to those used in this study.